Backdoor: Houses That Swim

Floating homes redefine what qualifies as a buildable lot

According to Dan Wittenberg, two-thirds of the earth still has
not been developed. He's talking about the blue parts on the globe,
not just the green parts, and while his comment is delivered
tongue-in-cheek, he's driving at a point that requires us to
rethink what we mean by "real estate." For Wittenberg, president of
International Marine Floatation Systems of Vancouver, B.C., Canada,
the surface of the water is the new frontier in coastal
living.

Moored in Seattle's Lake Union, this two-bedroom,
2,000+-square-foot floating home was built for a former vice
president of Microsoft by International Marine Floatation Systems.
The architect, Gene Morris, squeezed every bit of usable space out
of a 16-foot height limit without making the structure look like a
box.

Floating neighborhoods have a long history in delta regions
worldwide. Seattle, Portland, and San Francisco all have thriving
houseboat communities that have gradually become stable with homes
that are more house than boat. And as a development scheme,
floating communities have found traction in the Netherlands, where
"amphibious houses" sited along waterways provide some relief in
that low-lying, densely populated country.

The home's foundation includes an underwater observation room
with a porthole for viewing local marine life.

Floating security. The difference between a floating home and any
other is (mostly) just the foundation, insists Wittenberg. "It's
still a permanent, unsinkable foundation, not a hull," he explains.
"The platform can't fill up or capsize. You can even drill through
it, as we do all the time to allow for drainage of surface
walkways."

The foundations consist of concrete-encapsulated foam. The art and
science of building one is finding the right balance between
ballast (concrete) and buoyancy (foam). "Nothing we do is really
that new. Archimedes figured this out long ago," Wittenberg
explains. His team has simply developed the engineering and the
business. IMF typically works with builders, providing the
engineering and coaching to get them through the construction of
the foundation. Once the foundation is in place, the home goes up
just like any other, and it has to meet code just like any other
residence.

"Amphibious homes" built by Dutch construction company Dura
Vermeer start at 260,000 euros (approximatel $347,000). The
foundations, which rest on the bank, are hollow concrete cubes
designed to float, and power, water, and waste are delivered
through flexible conduits that accommodate movement whenever the
Maas River floods.

House sizes are comparable as well. IMF house projects typically
range from 3,000 to 5,000 square feet, with values running
correspondingly high. "A $1M home on a $1M water lot is pretty
typical," Wittenberg says. "The bank doesn't see too much
difference, though insurance companies sometimes do. We ask for
homeowner's policies on these. It's not a boat; it won't sink, so
marine rates do not apply."

Bullish on buoyancy. Wittenberg sees more municipalities becoming
comfortable with the idea as industrial-owned waterfronts have
given way to public access. Sewage is often a concern, but
Wittenberg says it's easy to demonstrate how the homes hook up to
municipal sewer lines with flexible lines and lift pumps to move
the waste ashore. This doesn't entirely quiet opposition from
environmentalists, however. "There are always factions that want to
shut down any new development. But if you really want to improve
the quality of our waterways, let people to live on them," urges
Wittenberg. "People are much less tolerant of pollution in their
own backyard." — Clayton DeKorne